It is known to provide modular elements of generally quadrangular shape and provided with interconnecting means along its sides for joining with adjacent modular elements. For instance, such modular elements may be tiles which are assembled to form a complete floor covering of a dimension in accordance with a floor to be covered without having to discard an inordinate amount of tile material which would be the case if the floor covering would consist of a large sheet to be cut out to suit the shape and size of the floor to be covered.
It is also known to provide solar panels with passageways incorporated therein for the circulation of a heat transfer medium. However, such panels are large panels and difficulty is often encountered in sizing the panels to suit the particular roof in which they are intended to be installed and also difficulty is also encountered in joining the passageways of the panel to fluid discharge and supply piping.
It is known to provide separate cylindrical conduits to protect underground electric power cables or telephone lines, said conduits adapted to be arranged side by side and stacked in vertical rows by means of spacers and adapted to be connected in end to end relation by junction collars. It is known that such separate conduits often break during their handling and that their positioning within a trench is time consuming.